I have no idea where the “Earth is only 6000 years old” argument comes from.
If it comes from counting the years from Adam’s age at death, and then adding all the subsequent generational ages, then it ignores time in the Garden of Eden (a spiritual place of Earth). For all we know that Adam and Eve were residing in this garden for billions of years as they were immortal.
There are many metaphors used in scripture and it is difficult to be at all scientific. But the key thing for a scientist to discern from scripture is that it cannot be falsified. It is written in a way that no firm scientific finding can render it fraudulent. That in itself is amazing.
This is not to say that scripture is scientifically provable, it merely points out that biblical scriptures are not contradicted by science such as the example I just gave that Adam and Eve could have existed in an immortal state for billions of years before expulsion.
The Resurrection is not provable scientifically nor is it falsifiable. This is what is amazing about the biblical scriptures, that the writings are not found to be false by current science and technology.
What amazed me was in reading of Moses on Mt. Sinai questioning direct to God “Who Are You?” and the answer blew me away; “I AM THAT I AM”. This is a tautology, always true X Implies X.
One can’t prove the existence of God. One can’t disprove the existence of God.
So would that make scripture in error as to the age of Adam at his death?